Preparation And Electrochemical Performance Of Si/RGO Composites For Lithium Ion Batteries

The silicon material has a high theoretical specific capacity(4200 mAh/g),and has a lower discharge platform,safe and non-toxic and rich in reserves,so the silicon material becomes the ideal high specific capacity lithium ion battery anode material.However,silicon is accompanied by a large volume expansion(up to 420%)during the intercalation process,and the conductivity is poor,limiting its commercial use.In order to effectively solve the problem of the volume change of silicon material during the cycle,we have prepared the Si/RGO with high temperature reduction by electrostatic self-assembly method with Si as the carrier with good mechanical properties and electrical conductivity.Composites were prepared by changing the preparation conditions.The structures and electrochemical properties of Si/RGO composites were studied.Si/GO composites were prepared by the ratio of Si and GO in the ratio of 2:1,1:1,1:2:1:4,respectively.When the mass ratio of Si to GO was 1:1,the best performance was 817 mAh/g at the current density of 0.05 rmA/crm2,the first Coulomb efficiency was 71%,and the capacity tyretention rate was 52.9%after 21 cycles.Then Si/RGO composites with Si and GO mass ratio of 1:1 were prepared by reduction of Si/RGO composites at 450 ?5 600 ? and 750 ? respectively.The effects of reduction temperature on Si/RGO composites were investigated.When the reduction temperature has the best overall electrochemical performance at 600 ?,the first discharge capacity is 939 mAh/g at a current density of 0.05 mA/cm2,the first coulomb efficiency is 66.67%,and the discharge capacity is maintained after 21 cycles Rate of 51.2%.The Si/RGO composites were prepared by Si and RGO composites at 60 rm and 200 nm respectively.The effect of Si particle size change on Si/RGO composites was investigated.It was found that the Si particle size was reduced and the discharge capacity of Si/RGO composites was Is reduced,but its cycle performance and magnification performance has increased.